Abstract

While little is known about the actual diet of free-ranging anoas, a study on their digestive physiology yielded results similar to other intermediate feeders. Among the ruminants, this species is particularly interesting, as, on the one hand, most of its closer relatives – the bovini, i. e. cattle and buffaloes – show extreme adaptations to grazing niche, but on the other hand, the anoa has a (secondarily) reduced body size usually associated with a more intermediate or browsing dietary niche. Here, we report the digestive macroscopic anatomy of a 21 year-old, 53 kg captive lowland anoa that was euthanised after a longer period of therapy-resistant diarrheoa and inability to stand. The results were compared to measurements published for other ruminants. The anoa showed several anatomical characteristics typical for the bovini (and considered typical for other grazers), such as an unpapillated dorsal ruminal mucosa, unpapillated, thick rumen pillars, pronounced reticular crests with secondary and tertiary crests, four orders of omasal laminae, and a large masseter muscle. In contrast, the omasal laminar area was small compared to data published for other species, and the parotis glands were comparatively large. The findings represent an unusual combination of anatomical characteristics for a ruminant that should be corroborated in more individuals, and could represent a retrograde change from a grazing back to an intermediate adaptation. It could be suspected that the anoa can make better use of grass-based diets than other intermediate feeders.